Return Home

	Renewable Energy Solar Power A tiny of the Sun's energy will supply our power needs many times over. Wind Energy Wind power is the conversion of wind energy into more useful forms.

	Environmentally Clean Energy Hydrogen Fuel Cells Hydrogen is considered a very promising candidate for alternate fuel. Biofuel Biodiesel is safe, biodegradable, and reduces air pollutants. Methanol/Ethanol Methanol and ethanol have long been considered for fuels.

Hydrogen Fuel Cells in Cars

Hydrogen has long been considered one of the most promising candidates for alternate fuel. Once the darling of the alternative energy world, hydrogen has been on the skids lately, with critics complaining that storage and production difficulties make it impractical and uneconomical as a fuel source. In addition, petroleum conglomerates are devising cleaner car fuels.

The underlying premise of a hydrogen economy is that fuel cells will replace internal combustion engines and turbines as the primary way to convert chemical power into motive and electrical power. The reason to expect this changeover is that fuel cells, being electrochemical, can be more efficient than heat engines. Currently, fuel cells are very expensive, but there is active research to bring down fuel cell prices.

Fuel cells work with hydrocarbon fuels as well as pure hydrogen. If and when fuel cells become cost-competitive with internal combustion engines and turbines, one of the first adopters will be large gas-fired power plants.

Hydrogen is the most abundant element in the universe. It also has an excellent energy density by weight, which leads to it being used for spaceships like the space shuttle. Emissions of a hydrogen-oxygen fuel cell, in theory, consist of pure water. The fuel cell is also more efficient than an internal combustion engine. The internal combustion engine is said to be 20-30% efficient, while the fuel cell is 75-80% efficient.

A fuel cell works like a battery but does not run down or need recharging. It will produce electricity and heat as long as fuel (hydrogen) is supplied. A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive electrode (or cathode)—sandwiched around an electrolyte. Hydrogen is fed to the anode, and oxygen is fed to the cathode. Activated by a catalyst, hydrogen atoms separate into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity. The protons migrate through the electrolyte to the cathode, where they reunite with oxygen and the electrons to produce water and heat. Fuel cells can be used to power vehicles or to provide electricity and heat to buildings.

There is concern about the energy-consuming process of manufacturing the hydrogen. Manufacturing hydrogen requires a hydrogen carrier such as a fossil fuel or water. The former consumes the fossil resource and produces carbon dioxide, while electrolyzing water requires electricity, which is mostly generated at present using conventional fuels (fossil fuel or nuclear power). While alternative energy sources like wind and solar power could also be used, they are still more expensive given current prices of fossil fuels and nuclear energy.

There are also issues in simply storing Hydrogen gas. Although Hydrogen gas has good energy density per weight, it has a poor energy density per volume. Hence it requires a large tank to store it. Increasing gas pressure would improve the energy density per volume, making for smaller, but not lighter container tanks (see pressure vessel). Compressing a gas will require energy to power the compressor.

However, some believe that the hydrogen fuel cell concept has promise, and hydrogen research continues to be funded. In 2004, the Department of Energy said it would spend $350 million over four years on hydrogen research.

Hydrogen will also cut down on greenhouses gases, its advocates say, because only water comes out of the tailpipe. However, manufacturing hydrogen, which involves combining methane with water and heating up the mix to 815 degrees Celsius, produces 9.3 kilograms of carbon dioxide for every kilogram of hydrogen. Some companies are tinkering with ways of sequestering manufactured carbon dioxide in underground caves and other storage facilities to keep it from getting into the atmosphere.

Car manufacturers acknowledge that the concept won't take off unless such problems can be conquered. Filling stations will also have to be built. But they believe that cars fueled by hydrogen could hit the road sometime between 2015 and 2020.

Although Hydrogen fuel cells have many critics, working hydrogen-fueled cars are in testing even today. Kevin Eslinger, a student of UC Davis Institute of Transportation Studies, is studying a university project Toyota SUV that runs on a hybrid electric/hydrogen engine. "We drove this past 100 miles per hour," Eslinger said. And it accelerates as well as a standard gas car, he added.

Toyota, Ford, Volkswagen, and BMW are also interested in hydrogen-fueled cars. Toyota has a car that gets about 60 miles per kilogram. Ford and Volkswagen have similar cars that can reach a speed of 80 mph. BMW The carmaker is experimenting with an engine that burns hydrogen directly in combustion. They claim that this will lead to greater horsepower. According to sources, BMW will run on liquid hydrogen rather than compressed hydrogen. Ethanol and methanol fuel cells are slowly being pushed aside in the wake of hydrogen-fuel cell advances.